1. Field of the Invention
The present disclosure relates to image processing for processing eye images.
2. Description of the Related Art
An eye examination is widely practiced for early diagnosis of lifestyle related diseases and diseases that rank high among the leading causes of blindness. A scanning laser ophthalmoscope (SLO), hereinafter referred to as an SLO imaging device, is an ophthalmologic instrument that uses the principles of a confocal laser microscope. An SLO imaging device performs raster scanning of the fundus with measurement laser light and acquires a planar image of the retina from the intensity of return light with high resolution and high speed.
There have been developed some SLO imaging devices that have an adaptive optics (AO) system for measuring aberrations of the eye to be examined with a wavefront sensor and correcting aberrations of measurement light occurring in the eye to be examined and aberrations of return light with a wavefront correction device. Such SLO imaging devices are referred to as AO-SLO imaging devices. AO-SLO imaging devices enable image acquisition with high lateral resolution, allowing detection of retinal capillary vessels and visual cells. Johnny Tam and Austin Roorda, “Enhanced Detection of Cell Paths in Spatiotemporal Plots for Noninvasive Microscopy of the Human Retina,” Proceedings of 2010 IEEE International Symposium on Biomedical Imaging, pp. 584-587, April 2010, discusses a technique of recognizing a moving range of blood cells as a vessel area from an SLO image that is focused near visual cells of the healthy eye, and measuring blood flow behavior including the moving speed of blood cells. However, SLO images focused near visual cells do not always allow accurate identification of vessels because vessels themselves are not in focus.